Patent Document 1 as a related art sets forth:
“An evaporation cooling apparatus including: an evaporator for boiling and evaporating a cold/heat evaporable liquid such as water under a lower pressure than an air pressure; a condenser for condensing vapor generated in the evaporator by a cooling evaporable liquid such as water; a cold/heat indirect heat exchanger installed at a load side such as a site to be cooled with air conditioning; a cooling heat exchanger using the air as a cooling source; a cold/heat circulation means for circulating a cold/heat evaporable liquid in the evaporator to the cold/heat indirect heat exchanger; and a cooling circulation means for circulating a cooling evaporable liquid in the condenser to the cooling heat exchanger, further including a vapor compressor such as a Roots compressor in a vapor duct extending from the evaporator to the condenser.
In the evaporation cooling apparatus of the related art, a cold/heat evaporable liquid is cooled by boiling and evaporation in the evaporator to a specific temperature required at the load side such as a site to be cooled with air conditioning, and the vapor generated through boiling and evaporation is guided to the condenser and then condensed by a cooling evaporable liquid using the air as a cooling source. The vapor generated in the evaporator is compressed by the vapor compressor into the condenser, whereby it is possible to cause a larger difference in temperature by a compression ratio between the evaporator and the condenser, as compared with the case where the vapor compressor is not used. Accordingly, even in the case where an air temperature as a cooling source is high, a temperature of a refrigerant evaporable liquid that is supplied to the load side can be lowered than an air temperature by a temperature difference equivalent to the compression ratio.
In the case of using a Roots compressor as the vapor compressor, for example, a compression ratio of vapor can be obtained with a temperature difference of about 15° C. As a result, it is possible to cool down reliably an evaporable liquid supplied to the load side to a low temperature of about 17 to 20° C., even if a temperature of the cooling evaporable liquid cooled by the air as a cooling source for the cooling heat exchanger, that is, a temperature of the cooling evaporable liquid supplied to the condenser reaches 32 to 35° at a maximum in the summer season or the like.
Patent Document 1: Japanese Unexamined Patent Publication No. 2006-97989